"It may sound stupid to you, but for the person who uses physical distance as another line of defence, who rarely touches even their closest friends with as much as a hand on the should in greeting, touching like that requires trust." Remus didn't think he could even begin to point out the trust issues involved in requiring oaths for any reason. "For the person who thinks of something as simple as the clothing they wear as a form of armour, letting themselves be seen in nothing more than their own insecurities requires trust."
Smiling as well, Remus agreed. "They both do. James and I could give Sirius a bit of what he missed out on with Regulus while they were growing up -- and as two only children, we loved the idea of having 'brothers'. But, we couldn't ever replace his real brother. Wouldn't want to." And knowing that was part of why Remus had been so insistent when he had the chance to get the brothers talking again.
"I'll be fine, James. I promise. It was a momentary twinge because I moved wrong." He wouldn't want to have to do any rapidfire wandwork at the moment. But, fine was a good word. "Believe me, it really is nothing I haven't dealt with before."
Remus had to shake his head again, listening to James. "That's part of the point, though. Learning the theory now helps in making that instinctive choice when it's necessary. It's like knowing the physics behind how and why an arrow in flight travels the way it does, how different environmental conditions affect it. The archer studies those things in advance, so when they're on the field in a high wind condition, they don't have to think about trajectory or force. They just knock the arrow and shoot, knowing they'll hit the target.
"It's not a game to them," he added with a worried frown. "They have to think of more than just you confronting Voldemort. They have to consider his Death Eaters as well. And many of them you do want alive for information."